The present invention relates to a presence information management system that manages status information on a user and a terminal, and more particularly to a technology that allows an apparatus, responsible for session control and management, to notify a change in the status of a user or a terminal on behalf of the user or the terminal.
The concept of “presence” has been discussed mainly by the IETF's (Internet Engineering Task Force) impp (Instant Messaging and Presence Protocol) working group (for example, see RFC 2778), and a presence information receiving/sending method using a communication protocol, named SIP (Session Initiation Protocol), was proposed (for example, see RFC 3265). In addition, development of a presence server dedicated to the management of information describing such a presence is now under way.
On the other hand, the concept of presence is embodied in the so-called IM (Instant Message), so that, immediately when a user to whom a message is sent goes on-line, the message is notified to that user.
Although not equivalent to “presence” that is a generalized concept, an information notification service providing some aspect of presence information has been used even on a conventional analog telephone. An example is a notification service that sends an answer-phone message to the calling side when the recipient is absent.
FIG. 9 shows an example of a conventional system using presence information. In the system using presence information shown in FIG. 9, a terminal 1 has the presence information update function 200. The terminal 1 uses this function to send a packet, which includes presence information, to a session control server 3 that has a packet relay function 210 and, via the session control server 3, delivers the packet to a presence server 7 that has a presence information management function 220.
FIG. 10 shows another example of a conventional system using presence information. In this example, presence information is notified and updated directly between a terminal 1c and a terminal 1d without using a presence server. However, the terminal, in both FIG. 9 and FIG. 10, requires a function to process presence information. Especially, in the mode shown in FIG. 10, the terminal requires not only the presence information update function 200 but also the function which receives and manages presence information 250 that also has the display function.
In a conventional system using presence information such as the IM service, a program on the client side must have an ability to notify a change in the presence status. The same holds true for a PSTN (Public Switch Telephone Network) and, for a service that notifies a user's answer-phone message to a caller, the telephone user must set the answer-phone message in the telephone. That is, the telephone requires a function that notifies presence information to the caller.
It is an object of the present invention to enable a terminal user, who uses a terminal with no function to notify and update presence information, to receive a service that uses presence information.